Flooded Forests Research Articles

English

The Amazonian rainforest is critical to our shared human future. Therefore, we need to understand the structure and function of their forests and soils are a critical part of that investigation. Towards that end, soil samples were taken in eight different forests, both non-flooded (terra firme-low forests, terra firme-high forests, white sand-varillal forests, white sand-chamizal forests and palm forests) and flooded by black-water (high restinga, low restinga and tahaumpa forests), at two locations in Loreto Province, Peru and analyzed for soil pH, soil organic matter, and soil nitrogen (N), phosphorus (P), and potassium (K). Results showed that: (1) soil pH of the non-flooded forests was very similar to flooded forests, but flooded forests became more basic as flooding increased in duration; (2) soil organic matter was lowest in the two non-flooded terra firme forests and increased as flooding increased in duration; (3) N was lowest in the palm forest, P was lowest in terra firme-low terrace forest and K was lowest in the terra firme-high terrace forest; (4) N decreased sharply as flooding duration increased, both P and K increased while (5) for some non-flooded forests there was a correspondence between soil fertility and floristic similarity. In conclusion, while flooding decreases pH and N, it increases soil organic matter, P and K.   Key words: Palm forest, restinga, tahuampa, terra firme, white sand forest.

Vochysia peruviana (Vochysiaceae), a new species from Flooded Forests, Madre de Dios, Peru

Vochysia peruviana is described and illustrated as a new species. It occurs in the Madre de Dios region of southern Peru, where is associated to flooded forests in the Amazonian lowlands. This species is placed in Vochysia section Ciliantha subsection Ferrugineae. It is compared with the most closely related species, V. ferruginea and V. floribunda.

Human management and hybridization shape treegourd fruits in the Brazilian Amazon Basin.

Local people's perceptions of cultivated and wild agrobiodiversity, as well as their management of hybridization are still understudied in Amazonia. Here we analyze domesticated treegourd (Crescentia cujete), whose versatile fruits have technological, symbolic, and medicinal uses. A wild relative (C. amazonica) of the cultivated species grows spontaneously in Amazonian flooded forests. We demonstrated, using whole chloroplast sequences and nuclear microsatellites, that the two species are strongly differentiated. Nonetheless, they hybridize readily throughout Amazonia and the proportions of admixture correlate with fruit size variation of cultivated trees. New morphotypes arise from hybridization, which are recognized by people and named as local varieties. Small hybrid fruits are used to make the important symbolic rattle (maracá), suggesting that management of hybrid trees is an ancient human practice in Amazonia. Effective conservation of Amazonian agrobiodiversity needs to incorporate this interaction between wild and cultivated populations that is managed by smallholder families. Beyond treegourd, our study clearly shows that hybridization plays an important role in tree crop phenotypic diversification and that the integration of molecular analyses and farmers’ perceptions of diversity help disentangle crop domestication history.

Quantification Des Stocks De Carbone De Trois Pools Clés De Carbone En Afrique Centrale : Cas De La Forêt Marécageuse De La Likouala (Nord Congo)

The data of carbon stock of central African swamps forests are very few. This study carried out an assessment of the carbon stock of living biomass and coarse woody debris of three biotopes (flooded forest, seasonal flooded forest, and terra firm forest) of Likouala swamp forest (North of Congo). The average of the carbon stock are 190.72±98.7 tC/ha, 39.69±21.24 tC/ha, and 9.45±6.6 tC/ha respectively for above ground, billow ground, and coarse woody debris. The carbon stock of our swamp forest tends to increase generally from the flooded forest to the terra firm forest. In addition, the average of the coarse woody debris carbon stock increases with the increasing of the above ground carbon stock.

BETA DIVERSITY OF BIRDS (Passeriformes, Linnaeus, 1758) IN SOUTHERN AMAZON

Abstract The importance of estimating the biological diversity and understanding how ecological specialization of species changes with spatially-organized habitats in undeniable. High beta diversity between neighboring places means an elevated number of species living within small distances, which usually are adapted to local conditions and highly vulnerable to anthropogenic actions as deforestation and burning. We investigated beta diversity of birds from the order Passeriformes in Southern Amazon, within landscapes with a large heterogeneous vegetation cover (habitats with flooded forest, dry forest, and marsh palm) through sound, observational, and photographic censuses. We marked 126 points in equidistant transects. A total of 148 species of birds were identified, distributed in 27 families. We found that 97% of the species foraged in flooded forest, 77% in dry forest and 19% in marsh palms, and only 18% foraged in the three habitats. An ordination analyses revealed which species showed the strongest preference to each habitat. The analysis for the Global beta diversity showed that this value is high (Whittaker: 7.7405), and the same pattern was obtained with the measure of pairwise dissimilarity. An influence of spatial distance was clearly observed in the cluster analysis and confirmed with a partial Mantel analysis; however, this was not observed at points that coincided with the transition and substitution of species. The influence of spatial distance in the dissimilarity index (beta diversity) was significant (r: 0.0608, p: 0.0049). The assemblage of species in small local populations with high beta diversity may be at risk if deforestation, selective logging, and poaching continue. In summary, this study provides important information on specific habitats with high beta diversity that may be at risk of destabilization of its populations due to continuing environmental changes imposed by humans.

Roloway Guenon ( Cercopithecus diana roloway ) and White-Naped Mangabey ( Cercocebus atys lunulatus ) Prefer Mangrove Habitats in Tanoé Forest, South-Eastern Ivory Coast

There are three primate taxa which have the same range in West Africa (eastern Ivory Coast and western Ghana): Miss Waldron’s red colobus Piliocolobus badius waldronae, the Roloway guenon Cercopithecus diana roloway and the white-naped mangabey Cercocebus atys lunulatus. They were previously listed as critically endangered; however, Cercocebus atys lunulatus was recently downgraded to endanger. A series of surveys have been conducted since the early 1990s in the tropical forests of Ghana and Ivory Coast to survey thesee taxa. In 2006, these studies led to the conclusion that the Tanoe forest, south eastern Ivory Coast should be considered a top priority site for primate conservation in West Africa. From February 2008 to March 2008; and in March 2009, we carried out field surveys in the Tanoe Forest over 22 days to gather updated distribution information to assess the conservation status of all diurnal primate taxa occurring in that forest, with special focus on the red colobus, Roloway guenons and white-naped mangabeys. During walk surveys of 429.3 km by three teams, we failed to observe any red colobus monkey. Diana roloway guenons were encountered at 0.10 groups/Km in the flooded forest vs 0.65 groups/ km in mangroves and white-naped mangabeys were encountered at 0.07 groups/km in the flooded forest vs 0.50 groups/Km in mangroves. Both these taxa were significantly more frequently encountered in mangroves compared to flooded forests. The high observation rate of Roloway monkey and white-naped mangabey in mangroves seems to indicate an adaptive strategy developed by these taxa to avoid hunting pressure. In addition, with its abundant foliage and the permanent presence of water throughout the year, mangrove offers food for monkeys.

The role of Lithodoras dorsalis (Siluriformes: Doradidae) as seed disperser in Eastern Amazon

ABSTRACT Ichthyochory is an important process responsible for the high diversity of plant species in tropical flooded forests. Thus, this study aimed to investigate the role of a catfish species, Lithodoras dorsalis, as seed disperser in the flooded forests at the Amazon River mouth, Brazil. Analyzing the stomach contents of 371 individuals of Lithodoras dorsalis, the Germination Potential (GP%) and Germination Speed Index (GSI) of seeds that were removed intact were investigated. This allowed us to evaluate the germination performance of two important species of plants in Amazonia, Euterpe oleracea (Açaí) and Montrichardia linifera (Aninga), after passage through the digestive tract of this catfish species. Given that digestion by L. dorsalis reduced the germination viability of M. linifera and that seeds were often destroyed during consumption, we suggest that L. dorsalis may have a limited role as seed disperser of M. linifera and instead mostly act as seed predator. However, for the species E. oleracea, L. dorsalis was a potential disperser, since the performance of germination of these seeds was improved after digestion. In addition, the number of seeds consumed was directly proportional to the catfish’s body size, reinforcing the role of doradids as potential seed dispersers in tropical forests.

Shift in the chemical composition of dissolved organic matter in the Congo River network

Abstract. The processing of terrestrially derived dissolved organic matter (DOM) during downstream transport in fluvial networks is poorly understood. Here, we report a dataset of dissolved organic carbon (DOC) concentrations and DOM composition (stable carbon isotope ratios, absorption and fluorescence properties) acquired along a 1700 km transect in the middle reach of the Congo River basin. Samples were collected in the mainstem and its tributaries during high-water (HW) and falling-water (FW) periods. DOC concentrations and DOM composition along the mainstem were found to differ between the two periods because of a reduced lateral mixing between the central water masses of the Congo River and DOM-rich waters from tributaries and also likely because of a greater photodegradation during FW as water residence time (WRT) increased. Although the Cuvette Centrale wetland (one of the world's largest flooded forests) continuously releases highly aromatic DOM in streams and rivers of the Congo Basin, the downstream transport of DOM was found to result in an along-stream gradient from aromatic to aliphatic compounds. The characterization of DOM through parallel factor analysis (PARAFAC) suggests that this transition results from (1) the losses of aromatic compounds by photodegradation and (2) the production of aliphatic compounds by biological reworking of terrestrial DOM. Finally, this study highlights the critical importance of the river–floodplain connectivity in tropical rivers in controlling DOM biogeochemistry at a large spatial scale and suggests that the degree of DOM processing during downstream transport is a function of landscape characteristics and WRT.

Environmental filtering of eudicot lineages underlies phylogenetic clustering in tropical South American flooded forests.

The phylogenetic community assembly approach has been used to elucidate the role of ecological and historical processes in shaping tropical tree communities. Recent studies have shown that stressful environments, such as seasonally dry, white-sand and flooded forests tend to be phylogenetically clustered, arguing for niche conservatism as the main driver for this pattern. Very few studies have attempted to identify the lineages that contribute to such assembly patterns. We aimed to improve our understanding of the assembly of flooded forest tree communities in Northern South America by asking the following questions: are seasonally flooded forests phylogenetically clustered? If so, which angiosperm lineages are over-represented in seasonally flooded forests? To assess our hypotheses, we investigated seasonally flooded and terra firme forests from the Magdalena, Orinoco and Amazon Basins, in Colombia. Our results show that, regardless of the river basin in which they are located, seasonally flooded forests of Northern South America tend to be phylogenetically clustered, which means that the more abundant taxa in these forests are more closely related to each other than expected by chance. Based on our alpha and beta phylodiversity analyses we interpret that eudicots are more likely to adapt to extreme environments such as seasonally flooded forests, which indicates the importance of environmental filtering in the assembly of the Neotropical flora.

Implications of boreal forest stand characteristics for X-band SAR flood mapping accuracy

Abstract Synthetic aperture radar (SAR) enables the mapping of flooding over large areas, regardless of cloud and weather conditions. Simplified classification approaches based on threshold levels of backscattering intensity are typical in operational flood monitoring. Backscattering intensity from floods over open non-forested areas is typically lower, whereas backscatter from forest floods is higher compared to non-flooded areas. However, distinction of flooded areas from non-flooded surface in semi-forested areas with low canopy closure (CC) or low tree height (TH) is expected to be difficult due to confounding effects of the different scattering mechanisms. The aim of this study was to investigate X-band SAR backscattering in flooded boreal forests with varying TH and CC, and to quantify in which cases floods would be difficult to detect with typical threshold-based classification methods. To further understand the SAR signal behavior in flooded forests, the total backscatter was modeled using the HUT (Helsinki University of Technology) semi-empirical forest backscattering model. HH-polarized Cosmo Sky-Med acquisitions from four different locations in Finland were analyzed against airborne LiDAR based forest data, ground observations and a high resolution digital elevation model. Floods were well detected in open areas and dense forests. However, as hypothesized, when TH was higher than zero but lower than 4–5 m, or when CC was higher than zero but lower than 15–20%, the detection was less successful. TH was found to have slightly more influence on the capability of X-band SAR to detect floods than CC. In our four test areas, namely Kittila, Kolari, Pudasjarvi and Evo, 85.3%, 89.1%, 82.7% and 73.9% of the total floods were detected, respectively, by a simple threshold value method. The model was able to successfully estimate the different backscattering components of the flooded forests in Kittila and Pudasjarvi, where the number of observations from all forest conditions was sufficient.

Litter and nutrient flows in tropical upland forest flooded by a hydropower plant in the Amazonian basin

Extensive areas in the Brazilian Amazon have been flooded for the construction of hydroelectric dams. However, the water regime of these areas affects the dynamics of igarapés (streams) in adjacent terra firme (upland forests). When the reservoirs are filled, the water levels of streams rise above the normal levels and upland bank forests are flooded. We investigated how this flooding affects the litterfall and nutrient input in the upland forests upstream of a hydroelectric dam reservoir in the Central Amazonia. When the reservoir was filled, the forests were flooded and produced more than twice the litter (8.80Mg·ha−1yr−1), with three times more leaves (6.36Mg·ha−1yr−1) than when they were not flooded (4.20 and 1.92Mg·ha−1yr−1, respectively). During flooding, the decomposition rate was four times lower in flooded forests (0.328g·g−1yr−1) than in control forests (1.460g·g−1yr−1). Despite this, the flooding did not favor litter or nutrient accumulation. Therefore, dam construction changes the organic matter and nutrient cycling in upland Amazon rainforests. This may influence the important role that they play in organic matter dynamics and could have consequences for the regional carbon balance and, ultimately, global climate.

Contrasting fire damage and fire susceptibility between seasonally flooded forest and upland forest in the Central Amazon using portable profiling LiDAR

Abstract Fire is an increasingly important agent of forest degradation in the Amazon, but little attention has been given to the susceptibility of seasonally flooded forests to fire. Satellite images suggest that forests flooded seasonally by nutrient-poor black waters are more susceptible to fire and may suffer greater fire damage than nearby upland forests. Reasons for this difference may include the presence of a root mat, more fine fuel as litter and a drier understory in the flooded forest. We investigated this difference in the field, hypothesizing that differences in the aboveground structure of the pre-burn forest can contribute to the difference in impacts of, and susceptibility to, fires. We employed a portable profiling LiDAR (PPL), first to compare damage between adjacent black water seasonally flooded and upland forests that were burned by the same fire event, and to then assess pre-fire canopy structure attributes known to affect fire susceptibility. For both assessments, we used PPL-derived metrics of leaf area and vertical and horizontal variation in the structure of vegetation in the canopy. Four years after the fire, the LiDAR metrics showed greater combined effects of high damage and slow recovery in the seasonally flooded forest; reduction of total Leaf Area Index (LAI) after burning was only 10% for upland forest but was 71% in the flood forest. Compared to unburned upland, the canopy of unburned flood forest had structural differences that increase susceptibility to fire, including drier microclimate. It had more gaps, a more open understory and a lower upper canopy. Small patches lacking canopy closure (LAI

Fatores Edáficos e as Variações Florísticas da Regeneração Natural em Duas Formações Florestais

The coastal ecosystems are more influenced by the characteristics of the soil along with the availability of nutrients act as a determining factor of the floristic composition and structure of a community. To verify the correlation between edaphics factors and species composition in two forests formations on the coastal amazon in the Environmental Protection Area Algodoal-Maiandeua, Maracana, Para we delimited three plots of 50 x 50 m (0.75 ha) in dry coastal forest and two (0.50 ha) in floodplain forest. We divided each plot into 50 plots of 2 x 2 m and we randomly identified and quantified all individuals with height ≥ 5 cm and ≤ 80 cm. In addition, we calculated the relative density. We used five single soil sample plots for edaphic analysis. The collection of soil for analysis was done using 5 single samples plots. To relate the gradients to edaphics component was performed canonical correspondence analysis (CCA). In the dry coastal forest the CCA showed greater correlation between Myrcia fallax , Pradosia pedicellata , Protium heptaphyllum and Parkia pendula with Fe, P, Cu, Ca, K and OM in the flooding forest, Symphonia globulifera , Virola surinamensis were high compared with CaCl2, KCl, H2O, Zn and N. Was constated distinctly the separation of the species best represented in the forests and the relationship with soil nutrients. Keywords : Dry coastal forest; Flooding forest; Nutrients of soil.

Primate Survey in a Bornean Flooded Forest: Evaluation of Best Approach and Best Timing

Abstract. Accurate determination of the abundance and distribution of animals, particularly endangered species, is a fundamental requirement for understanding their ecology and has important applications for their conservation. In Bornean flooded forests, various approaches have previously been used to conduct primate census, including foot-based land surveys and boat-based river surveys at different times of the day such as in the early morning and/or late afternoon. However, the accuracy of primate encounter frequencies and animal counts obtained using these methods has not been assessed. Therefore, in this study, we attempted to assess the accuracy of these methods used in different studies. We found that boat-based river surveys were more accurate than foot-based land surveys for evaluating the abundance and distribution of Bornean primates, particularly proboscis monkeys (Nasalis larvatus) and long-tailed macaques (Macaca fascicularis). Furthermore, based on our evaluation of boat-based river surveys...

Seasonality of reproduction of epiphytic bryophytes in flooded forests from the Caxiuanã National Forest, Eastern Amazon.

This work aimed to recognize the reproductive biology of the epiphytic bryoflora of phorophytes of Virola surinamensis (Rol. ex. Rottb.) Warb. in várzea and igapó forests in the Caxiuanã National Forest, to answer the following question: The reproductive period of the bryophyte species is influenced by the environment due the climatic seasonality present in flooded forests, being higher the occurrence of the sexual and asexual reproduction in the rainiest months? The bryophytes were identified and analyzed for the type of reproduction, sexual system and reproductive structures. In total, 502 samples of bryophytes were analyzed, resulting in 54 species, of which 34 were fertile. The comparison of the fertility of the species in different environmental conditions (dry or rainy, and igapó or várzea forest) was assessed using the chi-square test. The fertility of the seven studied species could not be defined by a pattern, considering the forest type and the seasonality. However, two species were associated to the forest type and two further species to the seasonality, showing that, for some bryophyte species, invest in constant fertility may be favoring the maintenance of their populations in tropical forests.

Floristic survey of flowering plants in a tropical coastal ecosystem in Veracruz, Mexico

Mexico is a megadiverse country and Veracruz is one of the states with the highest floristic diversity. The reserve of La Mancha in central coastal Veracruz comprises several vegetation types. In this site we conducted for a year, monthly surveys of flowering or fruiting plants in six vegetation types, considering the frequency of occurrence of different species. We found a total of 147 species (131 genera and 63 families). The families most represented were Asteraceae, Fabaceae and Verbenaceae. In addition, we found nine species that had not been reported in previous floristic studies. The highest taxonomic richness was observed in the tropical deciduous flood forest with wetland (59 species), while the highest diversity was found in tropical deciduous forest (ISI = 0.9562). We also found that the most similar vegetation types based on the composition and frequency of species were, coastal dune scrub, tropical deciduous forest and pioneer dune vegetation. The dominant plant biological form in La Mancha were herbs (40.41 %) followed by shrubs (23.97 %), vines-lianas (18.49 %) and trees (17.12 %). This study is the first to consider the frequency-occurrence of flowering and fruiting plants in La Mancha, covering six vegetation types through one year. The more relevant results of this study show the diversity of plants in different environments using the frequency of each species based on reproductive events. This information could be useful in future researches that evaluate plant-animal interactions, like pollination and seed dispersal.

Spatial and seasonal contrasts of sedimentary organic matter in floodplain lakes of the central Amazon basin

Abstract. In this study, we investigated the seasonal and spatial pattern of sedimentary organic matter (SOM) in five floodplain lakes of the central Amazon basin (Cabaliana, Janauaca, Canaçari, Mirituba and Curuai) which have different morphologies, hydrodynamics and vegetation coverages. Surface sediments were collected in four hydrological seasons: low water (LW), rising water (RW), high water (HW) and falling water (FW) in 2009 and 2010. We investigated commonly used bulk geochemical tracers such as the C : N ratio and the stable isotopic composition of organic carbon (δ13Corg). These results were compared with lignin phenol parameters as an indicator of vascular plant detritus and branched glycerol dialkyl glycerol tetraethers (brGDGTs) to trace the input of soil organic matter (OM) from land to the aquatic settings. We also applied the crenarchaeol as an indicator of aquatic (rivers and lakes) OM. Our data showed that during the RW and FW seasons, the surface sediments were enriched in lignin and brGDGTs in comparison to other seasons. Our study also indicated that floodplain lake sediments primarily consisted of allochthonous, C3 plant-derived OM. However, a downstream increase in C4 macrophyte-derived OM contribution was observed along the gradient of increasing open waters – i.e., from upstream to downstream. Accordingly, we attribute the temporal and spatial difference in SOM composition to the hydrological dynamics between the floodplain lakes and the surrounding flooded forests.

Malaria burden and anti-malarial drug efficacy in Owando, northern Congo

BackgroundIn the Republic of Congo, previous epidemiological studies have only been conducted in the south of the country where it is most accessible. Nationally representative data on the efficacy of new anti-malarial tools are lacking in the country. As an initial step to close the gap, clinical efficacy of two artemisinin-based combinations, artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL), was assessed in Owando, a city in equatorial flooded forest in northern Republic of Congo.MethodsUnder 12 years old febrile children attending public health facilities were screened for malaria parasites using lactate dehydrogenase (LDH)-based rapid diagnostic test (RDT) for malaria and microscopic examination of thick blood films. Patients with at least 1,000 asexual Plasmodium falciparum parasites/µl of blood were clinically examined, included after informed consent, and followed up for 28 days, according to the 2009 World Health Organization protocol. Patients were randomly assigned to co-formulated ASAQ (Coarsucam®) or AL (Coartem®) treatment groups. Plasmodium falciparum recrudescent isolates were compared to pre-treatment isolates by polymerase chain reaction (PCR) using msp1, msp2, and glurp genes to distinguish between re-infection and recrudescence.ResultsBetween November 2012 and February 2013, 857 under 12 years old febrile children were screened, of whom 198 (23.1 %) had positive RDT and 167 (19.5 %) positive thick films. ASAQ and AL efficacies were 92.7 and 94.2 % before PCR correction, respectively. After genotyping, the overall efficacy was 100 % for ASAQ and 98.0 % for AL.ConclusionThe data reported here represent partially the burden of malaria in 0–11 years old febrile children examined in public health centres of Owando city and serve as reference for further studies. Both artemisinin-based combinations were highly efficacious in patients under 12 years old with acute uncomplicated malaria. ASAQ was associated with more adverse events, which may reduce compliance in unsupervised treatment.Trial registration: ACTRN12612000940875

How livestock and flooding mediate the ecological integrity of working forests in Amazon River floodplains.

The contribution of working forests to tropical conservation and development depends upon the maintenance of ecological integrity under ongoing land use. Assessment of ecological integrity requires an understanding of the structure, composition, and function and major drivers that govern their variability. Working forests in tropical river floodplains provide many goods and services, yet the data on the ecological processes that sustain these services is scant. In flooded forests of riverside Amazonian communities, we established 46 0.1-ha plots varying in flood duration, use by cattle and water buffalo, and time since agricultural abandonment (30-90 yr). We monitored three aspects of ecological integrity (stand structure, species composition, and dynamics of trees and seedlings) to evaluate the impacts of different trajectories of livestock activity (alleviation, stasis, and intensification) over nine years. Negative effects of livestock intensification were solely evident in the forest understory, and plots alleviated from past heavy disturbance increased in seedling density but had higher abundance of thorny species than plots maintaining low activity. Stand structure, dynamics, and tree species composition were strongly influenced by the natural pulse of seasonal floods, such that the defining characteristics of integrity were dependent upon flood duration (3-200 d). Forests with prolonged floods ≥ 140 d had not only lower species richness but also lower rates of recruitment and species turnover relative to forests with short floods <70 d. Overall, the combined effects of livestock intensification and prolonged flooding hindered forest regeneration, but overall forest integrity was largely related to the hydrological regime and age. Given this disjunction between factors mediating canopy and understory integrity, we present a subset of metrics for regeneration and recruitment to distinguish forest condition by livestock trajectory. Although our study design includes confounded factors that preclude a definitive assessment of the major drivers of ecological change, we provide much-needed data on the regrowth of a critical but poorly studied ecosystem. In addition to its emphasis on the dynamics of tropical wetland forests undergoing anthropogenic and environmental change, our case study is an important example for how to assess of ecological integrity in working forests of tropical ecosystems.

Confirming the occurrence of the Endangered yellow-footed tortoise in flooded forests of the Amazon

Confirming the occurrence of the Endangered yellow-footed tortoise in flooded forests of the Amazon